Regenerative heat exchanger



y 17, 1960 J. s. COLLMAN ET'AL 2,937,016

REGENERATIVE HEAT EXCHANGER 3 Sheets-Sheet 1 Filed Jan. 16. 1956 INVENTORS 5. C'

Y 1960 J. 5. COLLMAN ET L 2,937,010

} REGENERATIVE HEAT EXCHANGER v Filed Jan. 16, 1956 3 Sh t ee s-Sheet 2 INVENTORS ATTOP/VE'X United States. Patent 2,937,010 REGENERATIVE HEAT EXCHANGER John S. Collman, Detroit, William A. Turnnen, Birmingham, and Paul T. Vickers, Royal Oak, Mich, assignors to General MotorsCorporation, Detroit, Miel1., a corporation of Delaware F Application January 16, 1956, Serial No. 559,389

2 Claims. (Cl. 257--270) This invention relates to heat exchangers and more partic'ularly to heat exchangers of the regenerative drum type.

Regenerative heat exchangers are generally associated with combustion turbine engines and the drum-type rea generator comprises a cylindrical matrix which rotates within a multiple duct casing that directs the engine intake and exhaust gases in separate paths through the matrix. Sruitable seals between the ducts divide the drum into a pair of semi-cylindrical sections within the ducts and the intake and exhaust gases are directed through the respective sections so that the matrix transfers heat from the hot exhaust gas to the cold intake gas as the drum rotates. i I

A regenerator of this .type should confine fluid flow through the matrix to a generally radial direction to reduce gas leakage between the ducts as an appreciable pressure differential exists between the intake and exhaust gases.

An object matrix for a regenerative heat exchanger which will permit fluid flow in a generally radial direction and which will prevent circumferential fluid flow.

A further object of the invention is to provide a drum. I

type matrix that is easy to manufacture, that has a high heat transfer capacity, that is resistant-to thermal distortion and that is of minimum size and weight.

In carrying the invention into effect, the drum-type heat exchanger is provided with a matrix of superimposed heat exchange elements which are dovetailed at their longitudinal ends into the grooved sidewalls of a pair of coaxially spaced support rings The individual matrix elements are thin metal plates which carry woven metallic screens with the wiring of the screens running generally parallel along the plate surfaces. The matrixelements are stacked in the rings and end-interlocked thereto to form an annular pack of heat exchange elements. The matrix elements are arranged so that alternating laminae of plates and screens are disposed radially to confine fluid flow. through the matrix to a generally radial path. The plate laminae prevent circumferential flow in the matrix and the screen laminae provide multitudinous, generally radial flow passages through the matrix. The individual screen laminae are preferably folded to provide a double layer of screening for each of the matrix elements, and the fold lines of the screens are preferably at an angle to the warp and'woof wires to minimize nesting of the screen layers.

of the invention is to provide a drum-type Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form'of the present invention is clearly shown.

, In the drawings: I

Figure 1 is a perspective of a woven screen which is used to fashion the screen portion of the heatexchange drum;

Figure 2 is a perspective of the woven screen folded on a bias to provide a double layer of screening with the warp and woof wires of the adjacent screen layers in criss-cross relation; T

Figure 3 is a segmental plan view of the folded edge of the screening;

7 2,937,010 PatentedMay 17, 1 960 ice , 2 Figure 4 is a partial perspective illustrating the screen and plate build-up of a matrix element;

Figure 5 is a partial perspective illustrating the screen and plate build-up of another matrix element;

Figure 6 is a partial perspective illustrating the screen and plate build-up of another matrix element;

Figure 7 is a partial perspective of a matrix element in assembled condition;

I Figure 8 is an exploded perspective of a matrix ele-' ment; m

Figure 9 is a perspective, partially broken away, of the regenerator drum;

Figure 10 is a partial section taken on the plane indicated by the line 10-10 of Figure 9; and a Figure 11 is a partial section taken on the plane indicated by the line 11-11 of Figure 10.

Referring to Figure 9, the regenerator comprises a drum 10 of assembled elements which are fashioned from stainless steel or other suitable high temperature material. A pair of coaxially spaced rings 12 and 14 have peripheral grooves 16 and 18 in their facing sidewalls that support a foraminous matrix 20. The matrix 20 comprises an annular pack of heat exchange elements 22 which have their longitudinal ends 24 and 26 dovetailed in the ring grooves 16 and 18 to form a rigid drum.

A typical matrix element 22, as seen in Figures 7 and 8, comprises a generally rectangular, thin, solid plate 28 having its ends 24 and 26 dovetailed to fill the ring grooves 16 and 18 when located along a radial plane in the drum. The plate 28 is formed by stamping-and has raised end lips 27 and 29 which'receive and locate re' inforcement blocks 30 and 32. The blocks 30 and 32 may have a slight taper and are spot welded to the plate 28 and provide a strong dovetail interlock with the rings 12 and 14. A woven screen strip 34 of substantially rectangular outline is spot welded to the surface of the plate 28 with the warp and woof wires 36 and 38 running lengthwise along the plate surface. The screen strip 34 is slightly narrower than the plate 28 so that the longitudinal edges 40 and 42 of the plate will protrude radially of the'screen strip edges 44 and 46 when the matrix elemeat 22 is assembled in the drum.

The longsides of the screenstrip 34 are preferably folded underat 44 and 46 to provide a double screen layera and b on the surface of the plate 28 and to conceal the jagged edges of the screening. The folds are on a bias to the warp and woof wires 36 and 38 so that a the wires in layer a will be in nonparallel or criss-cross relation to the Wires in layer b. The warp and woof wires of a Woven screen, as may be seen in Figure l, are sinuous and a better intermesh or nesting'of the screen layers a and b is had when the screening is folded on a bias as in Figure 2. The fold angle L is preferably 22% degrees when the screen mesh is rectangular to give greatest intermesh. V

' Theouter circumference of the rotor is greater than the inner and it is accordingly desirable that the heat exchange elements stack into a natural annular pattern. Figures 6 to 8 illustrate-one form of matrix element 22 wherein each end of the screen strip 34 is folded under to provide a double screen layer a and b of uniform thickness along the surface of the plate 28. This ,form of matrix element is hereafter referred to as a double layer element D. a V

- Figure 5 illustrates another form of matrix element 22 wherein the folded outer edge .44 of the screen strip 34 laps each side of the screen layer a which is extended to provide a triple screen layer a, b, c at the outer edge.

' The matrix element of Figure Sis accordingly of greater thickness along outer edge 44 than along-inner edge-46 and'is hereafter referred to as a tapered layer element T.

and it will be noted that the double layer elements D are disposed in alternating relation with the tapered layer elements T to provide an annular pack of heat'exchange elements and that a third form of element DD is used as the bottom element in the 10 stack-up. This third form of matrix element 22 is hereafter referred to as a double-double layer element DD for it has a double thickness screen strip 34 spot welded to each side of the plate 28 as may be seen in Figure 4.

The drum 10 is assembled by properly spacing the rings 12 and 14 and by consecutive insertion of the matrix elements 22 in the ring grooves 16 and 18. The rings 12 and 14 may be split radially for insertion of the elements 22 and thereafter joined, as by welding, to provide a complete drum.

The matrix'elements 22 may also be inserted into properly spaced and continuous rings by locating the elements at a tangent to the ring peripheries, by bowing the elements, by inserting the ends of the bowed elements radially into the ring grooves 16 and 18, by releasing the elements to cause spring-back to flat configuration and by rotating the elements into radial position so the dovetail ends 24 and 26 fully engage the complementary ring grooves 16 and 18. When the rings are filled to the point that additional matrix elements cannot be inserted, the semi-annular pack of already inserted elements is compressed in a peripheral direction to provide space for insertion of sufficient additional elements to fill the rings. The woven screens are sufficiently resilient to expand and form a solid annular matrix pack on termination of the peripheral compression.

The drum matrix is given greater rigidity by locating a relatively thick rib plate 50 in each 10 stack of elements. The rib plates 50 (see Figure 10) are dovetailed at the ends 24 and 26 to fit in the ring grooves 16 and 18 and are inserted similarly to the elements 22 although they must be cocked with respect to the drum axis during insertion as their thickness does not permit bowing.

'When the matrix elements 22 and the rib plates 50 are assembled in the rings 12 and 14 in proper sequence and spacing, a plurality of pins 52 and 54 are inserted'in radial bores 56 and 58 of the rings 12 and 14. A pair of pins is provided for each 10 segment; The pins 52 and 54 insure proper spacing of the matrix elements throughout the drum perimeter and maintain the elements in proper radial disposition. Gears 60 and 62 are then secured to the rings 12 and 14 to provide a drive means for the drum and to retain the pins 52 and 54 in the rings.

The gear drive may be dispensed with if desired and rotation of the drum may be achieved by curving the matrix elements 22 with respect to the drum radii so that gas flow through the matrix will power the drum in much the same manner as a radial flow turbine.

The heat exchange pack provides'a natural labyrinth sealing action as the matrix passes through the casing seal between the differential pressure fluid ducts. Reference maybe had to assignees copending application, B-24,344, Rotary Regenerator, for a sealing arrangement particularly adapted for the regenerator drum of this invention. The labyrinth sealing action is achieved because a multiplicity of spaced plates 28 are always present under the seal. The edges of the plates are in close proximity to the seal surface (as at 7 and 72in Fig. and the spaced plates therefore provide a series of orifices and expansion chambers for dissipation of velocity pressure.

The thin plates 28 are excellent heat exchange members and prevent circumferential gas flow in the matrix so that fluid leakage between the high and low pressure ducts cannot'take place through the matrix in the seal area. The screens 34 are highly efficient heat exchange members and permit free radial gas flow through the matrix. Fluid flow is directed through the woven screening in a direction generally parallel to the plane of the warp and woof wires in contrast to prior heat exchangers 4 which placed the screen wires in a plane perpendicular to the fluid path.

The drawings depict an actual heat exchanger and the following dimensions thereof may aid in visualization:

Drum O.D.--21%" Plate thickness.005"

Rib plate thickness /s Pin diameter%" Block thickness, thin end-.0S7"

Block thickness, thick end-.065"

Woven wire screen-01? diameter16 mesh While the preferred embodiment of the invention has been described fully in order to explain the principles of the invention, it is to be understood that modifications of structure may be made by the exercise of skill in the art within the scope of the invention which is not to be regarded as limited by the detailed description of the preferred embodiment.

We claim:

1. A drum-type regenerative heat exchanger comprising a pair of co-axially spaced rigid and integral rings each having a peripherally grooved sidewall facing the other ring, a foraminous matrix extending between the rings comprising an annular pack of heat exchange elements each disposed in generally co-planar relation with the axis of the rings and each having longitudinal ends dovetailed in the grooved sidewalls of the rings to form a rigid drum, and means for securing the matrix pack elements in said co-planar relation the matrix pack elements comprising thin plates and woven screen strips alternately disposed around the axis of the rings, the screen strips being sandwiched between the plates in full faceto-face surface contact to provide generally radial flow passages extending lengthwise through the drum, each screen strip being secured to an adjacent plate.

2. A drum-type regenerative heat exchanger comprising a pair of coaxially spaced rigid rings each having a peripherally grooved sidewall facing the other ring, a foraminous matrix extending between the rings comprising an annular pack of heat exchange elements each disposed in generally co-planar relation with the axis of the rings and each having longitudinal ends dovetailed in the grooved sidewalls of the rings to form a rigid drum, and means for securing the matrix pack elements in said coplanar relation the matrix pack elements comprising thin plates and woven screen strips alternately disposed around the axis of the rings, the screen strips being sandwiched between the plates in full face-toface surface contact to provide longitudinally extending and generally radial flow passages through the drum, eachscreen strip being secured to an adjacent plate, and comprising a length of screening having an end folded under to provide a relatively smooth-edged double layer screen strip, the fold edge being on a bias to the warp and woof wires of the screening to provide better nesting of the double layer.

7 References Cited in the file of this patent UNITED STATES PATENTS 902,812 Goetz et al. Nov. 3, 1908 1,603,026 Cook Oct. 12, 1926 1,843,252 Toensfeldt Feb. 2, 1932 2,037,164 Harrah Apr. 14, 1936 2,112,743 Poole Mar. 29, 1938 2,157,744 Welty May 9, 1939 2,368,732 Wallgren Feb. 6, 1945 2,615,685 Bowden et al. Oct. 28, 1952 2,686,154 MacNeill Aug. 10, 1954 2,701,130 Boestad Feb. 1, 1955 2,792,200 Huggins et al. Apr. 14, 1957 FOREIGN PATENTS Italy Sept. 29, 1951 

